New bacteria phylum discovered in hospital sink

Most of the life on Earth comes in the form of small, single-celled organisms. But even though we knew there was incredible diversity at the microbial level, these cells all look pretty similar under a microscope. For many of the bacterial species we've identified, the key step has been growing them in a flask so we can generate large enough numbers to study them.

Over the past decade, the advent of cheap DNA sequencing technology has helped the microbe discovery process along. Currently, we can sequence huge populations of microbes and get fragments of sequences that give us some sense of the full diversity of life. But these sequences tell us little more than the fact that a species exists. We still often know little about what it is and how it manages to make a living.

Now some researchers have managed to generate a genome sequence from a single bacterium, and they have used this technique to scan for new species in a biofilm isolated from a hospital sink. The results include the genome of a previously unrecognized phylum of bacteria, called TM6, that appears to be an obligate symbiote, perhaps living inside another cell found in the biofilm.